Income Taxes - Reconciliation of Statutory U.S. Federal Income Tax Rate to Company's Effective Income Tax Rate (Details)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. statutory tax rate	35.00%	35.00%	35.00%
Increase related to state and local taxes, net of U.S. income tax benefit	(499.90%)	1.30%	4.70%
Benefits and taxes related to foreign operations	(2796.30%)	(6.20%)	0.70%
Accounting pronouncement for equity compensation including foreign	(486.20%)	0.00%	0.00%
Rate change to deferred items related to Tax Cuts and Jobs Act	(5193.70%)	0.00%	0.00%
Other	89.20%	0.80%	0.50%
Effective income tax rate	(8851.90%)	30.90%	40.90%

Effective Income Tax Rate, from Continuing Operations, Before Noncontrolling Interests

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Effective Income Tax Rate Reconciliation, Changes in Accounting Standards, Share-based Compensation, Percent

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Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Change in Rate of Deferred Tax Assets and Liabilities, Percent

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I)
-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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